Process of separating chalcopyrite ores



Patented July. 14, 1942 2,289,996, rnoonss or sl'll'AgfilsNGCHALCOPYRITE Anderson W. Ralston and Ervin W. Segebrecht,

A, Chicago, Ill., asslgnors to Armour and Company, Chicago, Ill., acorporation of Illinois No Drawing.

Application November 13, 1939,

Serial No. 304,267

3 Claims.

This invention relates to the recovery of copper pyrites fromorescontaining the same, and it comprises processes wherein such oresare subjected to froth flotation in the presence of primary aliphaticamines having from twelve to eighteen carbon atoms and water-solublesalts thereof.

Chalcopyrite ores contain copper as a double sulflde of copper and,iron. In addition to the valuable .copper and iron constituents muchsilica in the form of quartz is found in the ore. At the present timethese chalcopyrite ores, and by that we mean any ore containing doublesulfide of copper and iron, are subjected to froth flotation for theseparation of the copper con stituents. Many diiferent flotation agentshave been proposed for effecting this separation. Many of them, however,are quite. expensive, relatively large amounts of costly complex organiccompounds being required. What is deisired in the art is a flotationagent which can be used under all conditions of acidity or alkalinity'inthe. aqueous slurry of ore pulp, which will not be expensive on acost-per-tcn basis, and which is readily available. We have nowdiscovered that primary aliphatic amines having from twelve to eighteencarbon atoms, as well as amine salts thereof, are highly effectiveagents for performing this separation. We have discovered that only verysmall quantities of these agents are required in contrast to much largeramounts of other flotation agents hitherto proposed. Moreover; we havediscovered that both the amines as such and their correspondingwater-soluble salts are effective. The importance of this is that theflotation can be performed successfully regardless of the acidityoralkalinity of the ore pulp. Consequently, we need not so control the pHvalue of the pulp that is on the alkaline side or the acid side, as

conditions might dictate.

Although the amine salts hate been suggested as flotation agents for theseparation of phos-' phate ores andother non-sulfide ores, we are notaware that these agents have been hitherto proposed for the separationof the speciflc ore of which the presentfinvention is concerned. In

amines, as well as their salts are highly effective. on the other hand,the primary amines alone are very much better agents for the frothflotation separation of phosphate ores, When phosphate ores are floatedwith amines the silica appears in the concentrate and the phosphatevalues in the tailings. When chalcopyrite is subjected to flotation itis the chalcopyrite which appears in the concentrate and the silica inthe tailings. 'Thus each and every ore behavesdifferently when subjectedto froth flotation in the presence of a primary aliphatic amine or itscorresponding water-soluble salt, and no pre-' dictions can be made withrespect to the behavior of one ore from the behavior of another.

We emphasize this point so that it may be understood that insofar as theamines and their salts are used as flotation agents, whether they arecommercially suitable with respect to cost, and what constituent in theorefloats, can only be determined by'experiment and cannot be predictedin advance.

In the present invention we have discovered that both the primary aminesand the corresponding water-soluble salts are effective, and each causescommercially practical amounts of the copper iron sulfide to beconcentrated in the concentrate.

our copending application filed of even date herewith, we describe theuse of primary aliphatic amine salts. as flotation agents for theseparation of copper sulfide from ores containing' the same. But, aspointed out in-that application, the amine 'salts are very much moreeffective than the corresponding amines. In the presentapplication wehave discoveredthat the 55 usually the hydrochloride or the acetate.

All those primary aliphatic amines, and water- 'soluble salts thereof,which have twelve or more containing twelve or more carbon atoms. ,Such

nitriles can be readily prepared by reacting mixtures of fatty acidswith ammonia, and the mixtures of fatty acids can inturn be obtainedfrom any of the common fats by saponiflcation and recovery ofthe fattyacids from the correspondingsoaps. a

For purposes of illustration we shall describe our invention withparticular reference to the use of dodecylamine and dodecylamineacetate.

This amine is readily obtained from the corresponding fatty acid.

The ore used had the following analysis: SiOz 48.11%, copper 12.01%,iron 17.51%. The ore was ground and admixed with water in the.

into a flotation cell flllea with water and t e suspension adjusted to apH of 8.1 by the addition of sodium hydroxide, Docecylamine, in theamount equivalent to 0.05 pound per ton of ore was then added and themixture subjected to froth flotation. The ore used amounted .to 494.65parts by weight. After flotation a concentrate amounting to 252.26 partsby weight was obtained. This concentrate analyzed'as follows: SiOz7.30%, Cu 24.50% and Fe 31.00%.

The tailings amounted to 252.39 parts by weight and analyzed as follows:SiOz 87.30%, Cu 2.33% and Fe 4.56%.

From this data it is apparent that 98.57% of the silica appeared in thetailings and 7.44% in the concentrate, 90.7% of thecopper appeared inthe concentrate and 9.03% in the tailings and 86.72% of the ironappearedv in the concentrate with 13.28% in the tailings. This gives acopper recovery of 90.97%, an iron recovery of 86.72%

i and a selectivity co-efiicient of 28.3.

Of special interest is the very small amount of primary amine used. Weknow of no separation hitherto practised on chalcopyrite which uses solittle flotation agent.

We' shall now give an example using dodecylamine acetate as a flotationagent. In this case the chalcopyrite ore analyzed 49.61% of .silica asS102, 15.21% of copper and 17.15% of water-soluble salts thereof.

On this basis all of the silica appeared in the tailings and none in theconcentrate, 97.42% of the copper appeared in the concentrate and 2.58%in the tailings, and 95.91% of the iron appeared in the concentrate and4.09% in the tailings. This gives a copper recovery of 97.42% and aniron recovery of 95.91%. The selectivity index is, therefore, infinitysince no silica appears in the concentrate.

From the foregoing results, which can be duplicated when otherprimaryamines and water-soluble salts having six or more carbon atomsare used, it is apparent that these flotation agents are highlyeffective when only small amounts thereof are used. Although more of theagent can be added to the slurry of ore such is wasteful.

We have not described the flotation step in detail since that is wellknown to those skilled: in the art. Our invention is primarily concernedwith the use of the aforesaid flotation agents for the separation'ofchalcopyrite from ores containing the same.

Having thus described our invention, what we claims is:

1. In the froth flotation of copper iron sulfide from ores containingthe same the step which comprises subjecting the ore to froth flotationin the presence of a flotation reagent consisting of at least oneprimary amine compound chosen from the group consisting of primaryaliphatic amines having at least twelve carbon atoms and 2. The processas in claim 1 wherein the flotation agent comprises dodecylamine.

3. The process as in claim 1 wherein the flotation agent comprisesdodecylamine acetate.

ANDERSON w. RALSTONs ERVIN w. SEGEBRECHT

